1. Technical Field
The present invention relates to a measuring method for determining a geometry of a concave portion.
2. Related Art
A conventional process for manufacturing of a semiconductor device employs a procedure, in which an interconnect trench and a via hole are formed in an insulating film, and a metallic layer is buried within the formed interconnect trench and the via hole to create an interconnect and a via. Geometries of the interconnect trenches and the via holes (hereinafter referred to as “interconnect trench and the like”) are controlled by suitably adjusting the etching time in the conventional process.
However, a problem of difficulty in precisely determining the geometries of the interconnect trench and the like is caused in the manner for controlling the geometry by adjusting the etching time.
To solve the problem, a manner for determining the geometry of the interconnect trench and the like by irradiating light over the interconnect trench and the like and analyzing light reflected from the interconnect trench and the like (for example, a scatterometry (optical critical dimension (OCD) measurement)) is proposed (see Japanese Patent Domestic Publication for PCT Application No. 2004-510,152, Japanese Patent Domestic Publication for PCT Application No. 2002-506,198 and Japanese Patent Domestic Publication for PCT Application No. 2006-512,561).
In such manner, parameters for determining the geometry of the interconnect trench and the like (for example, depth of the interconnect trench and the like, angle of the side wall with the bottom surface of the interconnect trench and the like, dimensional width in the intermediate-deep position of the interconnect trench and the like) are previously correlated with waveform of the reflected light, and the correlated parameters are stored in a database (library). Then, the interconnect trench and the like is irradiated with light and the reflected light is detected with a detector to acquire waveform of the reflected light. Then, the acquired waveform of the reflected light is referenced with waveforms stored in the database. If the acquired waveform of the reflected light is identical to a waveform stored in the database, then the geometry of the interconnect trench and the like is defined as the parameter for determining the geometry of the interconnect trench and the like correlated with the waveform in the database. Here, when the database is prepared, the parameters for determining the geometry of the interconnect trench and the like (for example, depth of the interconnect trench and the like, angle of the side wall with the bottom surface of the interconnect trench and the like, dimensional width in the intermediate-deep position of the interconnect trench and the like) are utilized in a predetermined function to obtain a calculated waveform. In such configuration, the respective parameters are set to be variable so as to be adapted to various types of geometries of interconnect trenched and the like.
In the above-described measuring method, the measurement result obtained by a scatterometry may be significantly different from an actually measured value by an observation with a scanning electron microscope (SEM).